Acanthamoeba is free-living protist pathogen capable of causing a blinding keratitis and granulomatous encephalitis. However, the mechanisms of Acanthamoeba pathogenesis are still not clear. Here, our results show that cells co-cultured with pathogenic Acanthamoeba would be spherical and floated, even without contacting the protists. Then, the Acanthamoeba protists would contact and engulf these cells. In order to clarify the contact-independent pathogenesis mechanism in Acanthamoeba, we collected the Acanthamoeba-secreted proteins (Asp) to incubate with cells for identifying the extracellular virulent factors and investigating the cytotoxicity process. The Asps of pathogenic Acanthamoeba express protease activity to reactive Leu amino acid in ECM and induce cell-losing adhesion ability. The M20/M25/M40 superfamily aminopeptidase protein (ACA1_264610), an aminopeptidase be found in Asp, is upregulated after Acanthamoeba and C6 cell co-culturing for 6 h. Pre-treating the Asp with leucine aminopeptidase inhibitor and the specific antibodies of Acanthamoeba M20/M25/M40 superfamily aminopeptidase could reduce the cell damage during Asp and cell co-incubation. These results suggest an important functional role of the Acanthamoeba secreted extracellular aminopeptidases in the Acanthamoeba pathogenesis process. This study provides information regarding clinically pathogenic isolates to target specific molecules and design combined drugs.

Freshwater shrimps are the most common crustaceans kept in an aquarium. This study was a survey seeking parasites infecting cultured freshwater atyid shrimps at aquarium stores in Tainan, Taiwan. We observed that atyid shrimps were infested with Vorticella and Scutariella. Scutariella is a common shrimp parasite; thus, we focused on Vorticella infection in the atyid shrimps. Vorticella aequilata-like pop TW, a freshwater peritrich ciliate, was isolated from the atyid shrimps. The morphological characteristics were investigated using live observations. Specimens from the population showed identical arrangement of the infraciliature and identical ITS1-5.8SITS2 region sequences. The zooids are bell-shaped, 40–58 μm wide and 47–70 μm in long in vivo. The food vacuole is variable in shape and is located in the middle of the cell. ITS1-5.8S-ITS2 sequences of Vorticella aequilata-like pop TW did not match any available sequences in GenBank. Phylogenetically, Vorticella aequilata-like pop TW clusters with the other Vorticella within the family Vorticellidae and nests with Vorticella aequilata in the subclade. Above all, the morphological characteristics and molecular analyses show that the investigated Vorticella is a Vorticella aequilata-like species. The phylogenetic analyses of ciliates based on the ITS1-5.8S-ITS2 sequences reveal that the Vorticella genus consists of Vorticella morphospecies and that taxonomic revision of the genus is needed. Morphometric criteria and molecular analysis were used to describe and identify the Vorticella specie and this study presents the first molecular identification analysis of the Vorticella species in the cultured atyid shrimps in Tainan, Taiwan.

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Manuscript type Empirical Research question/issue Estate tax planning has always been a primary concern of large shareholders when arranging the controlling shareholding structure of family firms. This paper provides evidence on the effect of a drastic change in estate tax on the shareholding structure of family‐controlled firms in Taiwan, as well as the impact of these changes on the firms' corporate value. We examine a 2008 policy change in Taiwan that substantially reduced the estate tax from a maximum rate of 50% to a single tax rate of 10%. Research findings/insights We analyze a 12‐year period from 2002 to 2014 looking at data of family‐controlled, listed companies with IPOs prior to 2001. The empirical results reveal a reduced motivation among controlling families to circumvent estate tax through altering the shareholding structure after the law change. The results also reveal a positive impact on firm value as a result of the reduction in the tax burden of controlling families. These findings contribute to the family firm and tax literature and provide insight into the effects of tax policy change on the controlling structure of family firms and the consequent benefits on firm value. Theoretical/academic implications To the best of our knowledge, this paper is the first empirical study that establishes a significant relationship between estate tax and tax‐avoidance behaviors reflected in the change of the shareholding structure of a family firm. Many research topics linking estate tax with other corporate governance issues in family firms are here unexplored. Practitioner/policy implications For the policymaker, this study highlights the increase of firm value due to a reduction in the estate tax rate. Moreover, a tax‐friendly environment can help the controlling family commit themselves to the proper management of the firm instead of expending effort on tax minimization to safeguard their wealth.

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